Ensure history doesn't become unreadable when an invalid card is read

[pipcet]

Hi! This minor fix avoids all history disappearing from the app when an "invalid" card (one for which card_type is undefined) is encountered.

(I've had to make a few minor changes to get things to compile on my machine at all, but those seem unrelated).

[Harry-Chen]

Thanks! But it looks like the commit history is not complete?

[pipcet]

Thanks! But it looks like the commit history is not complete?

I'm not entirely sure what you mean. It's a tiny change, yes, but one that is necessary. Using var instead of let here will mean that cardType may become undefined in line 921, and will be used in line 932.

That means the JSON object written to the database won't have a cardType property, since JSON drops properties with undefined values, and the application code relies on the cardType property always to be present, causing the disappearing history bug.

[Harry-Chen]

Thanks! I understand now.

[Harry-Chen]

Your fix is not correct -- it makes card_type always 'Unknown':

var card_type = 'Unknown';
{
  let { card_type, ...detail } = {card_type: 'A'}
}
console.log(card_type) // 'Unknown'!